When designing the data closet should be located in a non-centralized location but still have easy access for services and upgrades or repairs. I would consider using a class b network set up which would easily allow 145 users, computers or equipment to connect but still provide additional addresses and networks as the company expands within the next two years. As for IP address I would consider static IP address for all local computers and equipment within the company such as printers, routers user computers etc.
This will be easier to use and less expensive. With over 16,000 networks and 65,000 host address available there will be plenty of room for the company to grow. I would also consider having a wireless network using dynamic ip addresses leasing addresses to the user’s devices to allow users to connect there wireless devices to the network. All the systems we use today can work well with DHCP so it shouldn’t be a problem. Also you should consider having multiple domain and DHCP servers to provide load balancing, efficiency and safety in case of server failure.
DHCP should be used whenever possible DHCP is easier because there is usually not a need to manually assign and track IP addresses across a number of devices where a specific IP is not necessary, and use reservations for the static devices like Printers and A/P’s. And use static addresses for Servers. For example when recovering from a full power outage DHCP WILL be the LAST service to start. So if all servers/printers were DHCP you’d spend a day rebooting/console-login and getting a valid IP – users can do that for themselves. These are just some of the considerations that can be taken into account when creating a small business network.